132 Journal New York Entomological Society. [Voi. xx. 



Huachucas, and that the Crciiiastogastcr and beetle are specifically 

 identical in the two localities. The scale Lecanium phoradendri. 

 however, lives on the outer surface of the mistletoe and was not seen 

 by me, whereas the scale I observed. Pscudococcus phoradendri, lives 

 hidden away in the hollow bases of the stems. 



Schwarz's observations and my own, which were made inde- 

 pendently in different parts of Arizona, thus reveal the existence of a 

 peculiar ccenobiotic association, in which at least five or six dif- 

 ferent organisms regularly cooperate : a live oak, a mistletoe, a weevil 

 larva, one or two scale insects and an ant. The mistletoe is a parasite 

 on the oak, the weevil and the scales are parasites on the mistletoe 

 and the ant is, in a sense, a parasite on the beetle-larva and the scales, 

 since it owes its dwelling to the former and derives its food-supply 

 from the latter. The Scolytid beetle and the Lycaenid caterpillar ob- 

 served by Schwarz may also belong in this association, since the 

 former perhaps finds the proper conditions for its existence only in 

 mistletoe branches that have been injured by the weevil larva, and the 

 Lycaenid caterpillar inay court the attentions of the ants. Some resi- 

 dent entomologist in Arizona will probably find that the exhaustive 

 study of the ccenobiotic association here briefly outlined has not only 

 a theoretical but also a practical interest, for the Creniastogaster is to 

 be regarded as a useful forest insect, since it cultivates scales that are 

 injurious to a serious plant parasite of the live oaks and other trees. 



Each of the Creniastogaster nests, which I opened, contained a 

 single queen and in one nest a male specimen was taken. As these 

 phases have not been seen before I subjoin a description of them: 



Cremastogaster arizonensis Wheeler. 



Female (dedlated). — Length 5.5-6 mm. 



Head large, rectangular, as long as broad, with straight lateral and poste- 

 rior margins. Mandibles with 5 subequal teeth. Anterior border of clypeus 

 sinuately excised. Antenrial scapes reaching nearly half way between the 

 eyes and the posterior corners of the head. Terminal joint of the two-jointed 

 funicular club scarcely twice as long as the basal joint. Thorax elliptical, 

 flattened dorsally, narrower than the head ; posterior border of scutellum 

 overarching the metanotum. Epinotum abrupt, on each side with a small 

 tooth, which is not longer than broad at the base. Petiole and postpetiole 

 similar to those of the worker. 



Smooth and shining; mandibles and front of head more opaque; the 

 former, clypeus, front and cheeks longitudinally striated, the mandibles and 



